System and method for robotic camera calibration

A method, comprising:

• pre-calibrating a robotic camera so that an initial orientation of the robotic camera is known in a world coordinate system and associating each of a plurality of zoom levels used by the robotic camera with a respective intrinsic parameter value, wherein the robotic camera is configured to capture data corresponding to a position of a sports ball, the robotic camera being further configured to automatically adjust an orientation and zoom level in response to the captured data or an external command;
• detecting a first image position of the sports ball on a surface of a sports play area in an image coordinate system in a first image, the first image being captured with the robotic camera in a first orientation;
• reading a first zoom level from the robotic camera and a first intrinsic parameter value for the first zoom level of the robotic camera corresponding to the first image;
• determining the first orientation of the robotic camera based on a pan and a tilt of the robotic camera relative to the initial orientation;
• determining a three-dimensional line extending through the robotic camera and the sports ball in the world coordinate system based on the detected first image position of the sports ball, the determined first orientation and the first intrinsic parameter value for the first zoom level;
• and
• determining a three-dimensional position of the sports ball in the world coordinate system located along the three-dimensional line based on information extrinsic to the robotic camera,
• wherein the information extrinsic to the robotic camera includes information received from a three-dimensional model of at least a portion of the surface of the sports play area that encompasses the three-dimensional position of the sports ball, the three-dimensional position of the sports ball being determined by locating an intersection of the three-dimensional line and the three-dimensional model.

A processor coupled to a robotic camera configured to perform operations comprising:

• pre-calibrating the robotic camera so that an initial orientation of the robotic camera is known in a world coordinate system and each different zoom level used by the robotic camera is associated with a respective intrinsic parameter value, wherein the robotic camera is configured to capture data corresponding to a position of a sports ball, the robotic camera being further configured to automatically adjust an orientation and zoom level in response to the captured data or an external command;
• detecting a first image position of the sports ball on a surface of a sports play area in an image coordinate system in a first image, the first image being captured with the robotic camera in a first orientation;
• reading a first zoom level from the robotic camera and a first intrinsic parameter value for the first zoom level corresponding to the first image;
• determining the first orientation of the robotic camera based on a pan and a tilt of the robotic camera relative to the initial orientation;
• determining a three-dimensional line extending through the robotic camera and the sports ball in the world coordinate system based on the detected first image position of the sports ball, the determined first orientation and the first intrinsic parameter value for the first zoom level;
• and
• determining a three-dimensional position of the sports ball in the world coordinate system located along the three-dimensional line based on information extrinsic to the robotic camera,
• wherein the information extrinsic to the robotic camera includes information received from a three-dimensional model of at least a portion of the surface of the sports play area that encompasses the three-dimensional position of the sports ball, the three-dimensional position of the sports ball being determined by locating an intersection of the three-dimensional line and the three-dimensional model.